The object of the invention is to propose a device for end-side welding of plastic profiles, preferably pipes, which improves the weld seam or the inner bead as well as the outer bead of the weld seam and can be used for a wide range of different dimensions of plastic profiles.
This object is achieved according to the invention in that a reflection inner ring is arranged on the heating plate, wherein the reflection inner ring reflects the heat rays or IR rays of the heating plate onto the plastic profile inner side.
The device for end-side welding of plastic profiles, preferably pipes, includes tensioning devices for retaining the plastic profiles in a coaxial position in relation to one another. The tensioning devices are preferably arranged on a base plate, wherein at least one tensioning device can be displaced coaxially to the other in order to weld the plastic profile ends to one another.
A heating plate for contact-free heating of the plastic profile ends by means of heat rays is arranged between the tensioning devices in which the pipe ends are clamped. Heating cartridges which correspondingly heat the heating plate are preferably arranged in the heating plate. The heat rays, preferably IR rays, which are generated by the heated heating plate, strike the plastic profile ends, as a result of which they are heated. In order to ensure optimum heating of the plastic profile ends, a reflection outer ring is arranged around the heating plate. This serves to reflect the heat radiation or IR radiation of the heating plate onto its inner side and project it onto the outer lateral surface of the plastic profiles. This enables even heating up of the plastic profile ends and the heating is performed not only via the end side, but also via the outer lateral surface of the plastic profile ends.
A reflection inner ring is arranged on the heating plate so that improved and even heating of the plastic profile end from the inside can also be carried out. As a result of this, the heat radiation or the IR radiation which proceeds from the heating plate is reflected on the reflection inner ring and projected onto the inner contour or the inner lateral surface of the plastic profile ends or the plastic pipe ends. This enables even heating of the plastic profile ends which is the prerequisite for good welding. The heating plate is preferably formed as a round disc which has the advantage that the same heating plate can be used for a wide range of dimensions of plastic profiles or range of diameters of pipes. The heating cartridges can furthermore be arranged in the radial direction in the heating plate, preferably regularly.
The heating plate preferably has heating cartridges which are arranged distributed around and along the circumference in radially extending holes. As a result of the arrangement of the heating cartridges, the heating plate has a through-hole in the centre. This serves primarily to produce the heating plate or to incorporate the hole for the heating cartridges.
One advantageous configuration of the invention lies in the reflection inner ring being arranged in the through-hole of the heating plate. The plastic profile ends, preferably pipe ends, to be welded are aligned concentrically or coaxially to the reflection inner ring for heating, wherein the reflection inner ring projects into the inside of the plastic profiles or pipes and as a result the heat rays or the IR rays of the heating plate are reflected on the outer lateral surface of the reflection inner ring and strike the inner lateral surface of the plastic profile or pipe and thus support heating from the inside.
A reflection inner ring which is fastened only on the end sides of the heating plate and is not covered by a through-hole can of course also be imagined.
In order to achieve good reflection of the heat or IR rays, the reflection inner ring has a maximum roughness of 1.2 μm, in particular the bushings of the reflection inner ring.
The reflection inner ring is preferably produced from material which is capable of conducting heat, in particular the bushings.
The reflection inner ring furthermore brings with it the advantage that the through-hole in the heating plate, which is a result of production, is closed by the fitting of the reflection inner ring and air circulation can be avoided or prevented. As a result, undesired heat discharge does not take place.
The wall of the plastic profile ends is thus heated via the heat radiation which directly strikes the end sides of the plastic profiles from the heating plate as well as via the reflection outer ring which projects the heat radiation or IR radiation onto the outer circumference or the outer lateral surface of the plastic profiles and furthermore also via the reflection inner ring which also reflects the heat rays or IR rays of the heating plate and projects them onto the inner surface of the plastic profiles and even emits heat rays as a result of the heat absorbed by abutting on the heating plate.
The invention is also characterized in that the reflection inner ring is formed to have a changeable length. Since the width of the heating plate expands and contracts over and over again as a result of the heating and cooling, it is important that the reflection inner ring always follows the change in length and width. This means that if the heating plate expands as a result of heating, especially in terms of width or thickness, the reflection inner ring is correspondingly lengthened. If the opposite is the case, the reflection inner ring also contracts. As a result of this, the reflection inner ring is always guided in a fixed manner in the through-hole of the heating plate and precisely positioned. It is also advantageous if the reflection inner ring is in contact with the heating plate over a large surface area, thus producing good heat transmission.
The reflection inner ring has multiple parts. The reflection inner ring preferably contains two bushings. It has also been shown to be advantageous if the bushings are formed to be identical and are arranged in mirror symmetry to one another. It is also preferred if the bushings or one of its end sides touch the end sides of the heating plate. It has been shown to be a further advantageous configuration if the lateral surface of the through-hole of the heating plate is in direct contact with or touch the lateral surface of a cylinder region of the bushings.
In order to achieve the changeability in the length of the reflection inner ring, the reflection inner ring has tensioning elements which mutually tension the bushings. The reflection inner ring preferably has a bolt on which the bushings are arranged and are tensioned by means of tensioning elements.
The heating plate is arranged between the two bushings, wherein the bushings are mounted on the bolt and accommodate the change in length of the heating plate by means of tensioning elements.